As I've said above and in the other forums that you spew "knowledge", You are out of knowledge of which you post. I'm not a brake person, but I defer to MlBill and others that have been in the field for many years. Your posts on the various forums shows your knowledge must be true as you "think" you read it on the INNER NET.

I,have quick loads program that gives pressure from chamber to muzzle.
Give me some rifle data and load data and I will enter it and see what spits out.
I cant seem to get screen shots to work but I ran data for my M1a and my 168gn bullet and 41.5 grains of H4895
I got 8000psi at the muzzle?

I,have quick loads program that gives pressure from chamber to muzzle.
Give me some rifle data and load data and I will enter it and see what spits out.
I cant seem to get screen shots to work but I ran data for my M1a and my 168gn bullet and 41.5 grains of H4895
I got 8000psi at the muzzle?

I've seen "tanker" M1a's too - just for fun, want to check a 16" barrel? Temperature would make a bit of a difference if one was using aluminum for a brake. There's more than a few bolt guns that would run higher pressures (and temperatures!) than your M1a. Barrel life for a standard M1a load is a fair bit longer than some of the barrel burners out there.
BTW, how do you like using quick load? I've had to do some work ups in the past, and modern technology would have made the process far shorter.

I build pressure test barrels every day. On a 20" barrel in 5.56mm the port pressure at 4.5" from the muzzle is in the 10000psi range,from 60000psi at chamber. I can't see pressure dropping to 1000psi in another 4" .

If the pressure is so low at the muzzle, how is the brake going to be effective? Or is it just a placebo?

Pressure at muzzle would have zero effect on whether or not a brake would perform well. It is ALL about the velocity and mass of the gasses and how well the brake is able to capture that energy. After the bullet passes the out of the first port, it would be this same force that would be acting on all parts of the brake. It is not the same "pressure" that one would measure with sensors or strain gauges on the barrel, but rather the force of the gases(inertia) striking the rearward facing surfaces.

Originally Posted by eaglemike

There is no way I would install an aluminum brake on my personal rifle.

Smart man!

Originally Posted by eaglemike

There is wide variety in pressure at muzzle. Barrel length, powder burn rate, initial chamber pressure, and other factors can make a rather large difference in pressure at muzzle. I've seen brakes fail, and those that don't. I'd suggest StressProof, or something even better.

Just my opinion, based on my personal experience.
YMMV.......

.

Although there is no reason why "stress proof" steel could not be used, there is no real advantage over 4140 or 416. In most cases I prefer to make brakes out of the same material as the barrel it is going on... Unless it is going on a sleeved Al or composite wound barrel.

Compare the tensile and yield psi of 6061-6 v 304 stainless.
6061t6 is 45k and 40k
304ss is 73k and 31k.
The 6061 has a better yield strength. Not difficult to handle the psi at the muzzle of a standard length barrel. We used 26-30” depending. They were 1” brakes, drilled .02-.03” over bore. These were heavy hitters not 6.5cm or 243.

As I've said above and in the other forums that you spew "knowledge", You are out of knowledge of which you post. I'm not a brake person, but I defer to MlBill and others that have been in the field for many years. Your posts on the various forums shows your knowledge must be true as you "think" you read it on the INNER NET.

What knowledge am I spewing?
6061 specs are easy to find. Any metallurgist will tell you yield values are the more important when constructing something like this.
Pressure values at the muzzle for a 26” barrel are under 10k, easily. Didn’t make that up.
Butch, you love to give me a bad time anytime I post. I’m flattered but maybe you should try it before you disagree or defer to milbil. Again, I’m sure you know wind flags better than I do, so I’ll happily defer to you on that

Pressure at muzzle would have zero effect on whether or not a brake would perform well. It is ALL about the velocity and mass of the gasses and how well the brake is able to capture that energy. After the bullet passes the out of the first port, it would be this same force that would be acting on all parts of the brake. It is not the same "pressure" that one would measure with sensors or strain gauges on the barrel, but rather the force of the gases(inertia) striking the rearward facing surfaces.

Smart man!

.

Although there is no reason why "stress proof" steel could not be used, there is no real advantage over 4140 or 416. In most cases I prefer to make brakes out of the same material as the barrel it is going on... Unless it is going on a sleeved Al or composite wound barrel.

Stressproof has nice mechanical properties, and machines (and finishes) very nicely. Not everyone knows how easy it is to machine. I've also machined a fair amount of 416, as it's my choice for a free machining stainless.

Compare the tensile and yield psi of 6061-6 v 304 stainless.
6061t6 is 45k and 40k
304ss is 73k and 31k.
The 6061 has a better yield strength. Not difficult to handle the psi at the muzzle of a standard length barrel. We used 26-30” depending. They were 1” brakes, drilled .02-.03” over bore. These were heavy hitters not 6.5cm or 243.

Wouldn’t Try it on a 338Lapua with a 16” barrel.

You keep bringing up 304. I've not heard of any positive expressions here about machining 304. It's my opinion you are not making a solid, principled argument for your choice of material, using 304 for comparison. If you personally want to use 6061 for your brakes, it's your choice.
If you were going to choose a better material like 416, or 17-4, that would be a more valid comparison. These materials machine reasonably, obviously not the same as 6061 though.

The numbers for 6061t6 Mram10 cited are crap to start with... Although it is TRUE that typical vales are close to what he cited, ONLY MINIMUM values are specified for 6061t6. ONLY these MINIMUM values should be used unless you have the facilities to test tensile and yield strength. The CORRECT values are: tensile 42,000 psi yield 35,000 psi. HOWEVER, the fatigue limit is only 14,000 psi. STRIKE ONE!

Next 6061t6 Is NOT even the best choice of readily available aluminum alloys for this type of application... 7075-t6, 7075t651, 7075t7 or 7075RRA would be better choices. Each of these heat treats would be slightly better than the one before it. However, only the t6 is readily available (check McMaster-Carr). STRIKE TWO.

He clearly does NOT understand the nature of the materials he is working with! I believe this is what Butch is referring to when he used the expression "spewing knowledge". Mram10's "knowledge" is incomplete and dangerously lacking. Some times a little knowledge is worse than none at all...

i like it. Im still trying to figure out the ins and outs. Its come in handy though for looking at different powders and bullet combo and seeing a close out come of the internal balistics. Been using it for looking at different cast loads, which im finding is darn near spot on for velocities. Thats what Im looking for.
The application seems way to involved for my simple needs but getting to the range , setting up crony only to see im not where I need to be is frustrating.
Theres not a lot of cast load data out there. Especially for semi auto rifles and more modern stuff.
I run cast in many rifles in 200 yard matches.
I will be playing around with cast loads for the M1a soon

I've seen "tanker" M1a's too - just for fun, want to check a 16" barrel? Temperature would make a bit of a difference if one was using aluminum for a brake. There's more than a few bolt guns that would run higher pressures (and temperatures!) than your M1a. Barrel life for a standard M1a load is a fair bit longer than some of the barrel burners out there.
BTW, how do you like using quick load? I've had to do some work ups in the past, and modern technology would have made the process far shorter.

So many professionals giving the numbers for pressures but yet forgot something most of us where taught in 6th grade science class. Bimetallic (Galvanic) corrosion. The OP said a Stainless barrel with an Aluminum muzzle break. Aluminum is Anodic to stainless and begins corrosion at first contact. So basically the threads on both the barrel and the break will eventually dissolve. So, how do the pressure numbers work with thread decay?

Thanks very much for your reply. Someone above was saying that pressure was down to 1K or so at the muzzle. If some manufactures a brake(s), unless it's custom, it's likely not know what the actual pressure/temperature/etc will be. My point was that I (at least) would not assume a brake would be installed in a 1K environment. As many others have noted, 6061 is just a poor choice (IMHO) if I want it to live for more than a few shots. I wouldn't even bother to build one for testing on a firearm, might use to proof a program.
Material cost is not much, and machining time difference isn't a huge part of the cost either, comparing 6061 to 416. Raise the price by $10 to $40 to account to increased costs over 6061,and sell a far superior product. That's how I'd look at it, anyway. YMMV, of course.

snip// 4140 or 416. In most cases I prefer to make brakes out of the same material as the barrel it is going on.

good advice here...and also gcoders comment on galvanic corrosion...which should be a serious consideration...not to mention the added effect of the byproducts of combustion...it's a recipe for failure...today,tomorrow,10yrs...I know I don't want to be there.

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